1. Field of the Invention
The invention relates to an occupant protection device for a motor vehicle having at least one inflatable airbag, which upon activation leaves through an exit opening, normally closed by a panel or cover, into the interior of the motor vehicle. The device includes means independent of the airbag for removing the panel or cover.
2. Description of the Prior Art
In the case of the known occupant protection devices having inflatable front or side airbags for motor vehicles, the exit opening through which, in the event of a collision, the airbag leaves in the direction of the interior of the motor vehicle is generally closed by a panel or cover for safety reasons and because of outer appearance. The panel or cover is usually formed by part of an internal paneling of the motor vehicle, a steering wheel covering or a cover part of an airbag housing and is generally detachably fastened in such a way that, when the airbag inflates, it can be opened explosively or by impact of the airbag in order to clear the exit opening. In this case, the panel or cover is usually accelerated in the direction of the interior of the motor vehicle, so that the risk of injuries to the vehicle occupants being caused by the moving panel or cover cannot be ruled out.
To solve this problem, in German reference DE-A 42 17 174 there is proposed an occupant protection device of the previously mentioned type in which the airbag is arranged in a pivotable housing open on one side. The exit opening of the housing is normally closed by a part of the housing designed as a foam padding. In the event of an accident, the housing part is pivoted, before inflation of the airbag, with the aid of a pyrotechnic propellant charge, in order to remove the foam padding from the region of the exit opening and at the same time pivot an open exit side of the housing in front of the exit opening arranged in an instrument panel of the motor vehicle. In the case of the known occupant protection device, in the event of an accident, first of all the pyrotechnic propellant charge is automatically ignited by acceleration sensors or the like which then respond and, as a result, the housing is pivoted, so that its open exit side comes to lie in front of the exit opening and the airbag then automatically inflated by an associated gas generator is able to leave from the exit opening. Although this sequence of events which proceed automatically in the event of an accident can eliminate the possibility of occupants being endangered by the panel or cover, the period of time between the response of the acceleration sensor and the beginning of the inflation of the airbag is extended by decisive fractions of a second, which cannot be tolerated because of the brevity of the time period available, in particular in the case of side airbags. The reason for the time delay is the necessary acceleration of the housing and the time required for covering the pivoting path, during which it is necessary to wait since, in the case of the known occupant protection device, the ignition of the airbag gas generator may take place only when the open exit side of the housing is completely in line with the exit opening, because otherwise catching or tearing open of the airbag cannot be ruled out.
Occupant protection devices for motor vehicles which include sensors designed as proximity sensors, which respond even before the motor vehicle collides with another object, are already known per se, for example from German references DT 20 49 183 and DE 44 24 878 A1. These sensors usually comprise a transmitter and a receiver which measures the radiation emitted by the transmitter and reflected by an obstacle and determines from this the distance from the other object. However, the sensors of these known occupant protection devices always effect an activation of the airbag and do not serve for the removal of a panel or cover which closes an exit opening for the airbag.
Furthermore, an occupant protection device which, in addition to an impact sensor, comprises an additional proximity sensor is known from U.S. Pat. No. 3,684,309. In this case the proximity sensor effects the activation of the airbag, while the impact sensor serves the purpose of controlling the inflation of the airbag according to the force of impact.